MiG-23's TP-23 and TP-26 IRST

Whatever material is used in those windows has to be pretty durable given the speed of The MiG-23, & while there are more optical options, now, my only thought was that the material might be similar to the one used on the seeker on the infrared version of The R-40, as it came out around the same time as said plane, iirc, but all that I have been able to find is this cryptic description that leads absolutely nowhere. Perhaps there's a mistranslation going on, here, but I really have no idea.

R-40T was equipped with thermal GSN T-40A1. The T-40A1 shroud is made of heat-resistant Kemnium and optoceramic-based satallic. The homing head took target designation within ±55° and captured the target before the launch of the missile. The T-40A1 uses signal processing principles that provide a high degree of protection against false thermal interferences. R-40TD and R-40TD-1 missiles are equipped with 35T1 SNS.
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https://en.missilery.info/missile/r40
 
Sitall was a transparent material made in the USSR for optics:
https://en.wikipedia.org/wiki/Sitall
if kemniya is a typo for kremniya then that's silicon.

Google gives three possible translations:

The T-40A1 fairing is made of heat-resistant sitall based on kemnium and optoceramics
The T-40A1 fairing is made of heat-resistant glass-ceramic glass and optoceramics.
The fairing of the T-40A1 is made of heat-resistant glass ceramic based on silicon and optoceramics.
 
For historic reference, my old Russian avionics website (2004) entries on TP-23 and TP-26

TP-23 / Spektr​

tp-23.jpg
TP-23 IRST on MiG-23​
Infra-red search and track system fitted to MiG-23M. TP-23 was also fitted to early Su-24 models. Search limits on the MiG-23 installation were +3°/-12° in elevation and +30°/-30° in azimuth. TP-23 could detect a Tu-16 at 30 km, and a MiG-23 at 20km, on a pursuit course.
TP-23-1 fitted to export MiG-23MF, MiG-23ML
TP-23M modernised version developed for Soviet MiG-23ML. Search range of TP-23M against a Tu-16 target was increased to 35-40km, and against a MiG-23 to 25km.

TP-26​

tp26.jpg
TP-26 IRST on MiG-23​
Infra-red radar search and track system fitted to MiG-23MLA/MLD. Range is said to be up to 85 km for a tail-on engagement with an afterburning bomber-sized target, or 60km non-afterburning (Piotr Butowski says 60km maximum). IRST has 5 operating modes depending on the distance to the target. The sensor is mounted under the nose, behind a triangular glass fairing. Some pilots have suggested it has better performance than the MiG-29's KOLS.

TP-26Sh1​

Infra-red search and track system fitted to MiG-25PD. Presumably based on the TP-26. Range given as 45km against a high altitude bomber (aspect unknown).
 
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Checking my collection of scanned Soviet MiG-23 manuals, I autotranslated the TP-23 section from a MiG-23M maintenance manual. The only things I gleaned were:

  • The IRST was a monoblock removed in one piece for maintenance
  • TP-23 and TP-23-1 were both used on Soviet MiG-23M (likely TP-23-1 was just an improved version)
  • It's cooled by nitrogen
 
The TP-23 thermal direction finder and the ASP-23D optical sight, which were part of the MiG-23M weapon system, were also available on the previous modification, but since they were sufficiently tested on the MiG-23M, it makes sense to focus on this sighting equipment in relation to the "EM" modification. The TP-23 thermal direction finder was used to detect air targets by the IR radiation of their engines, allowing for covert target searches day and night. Unlike the radar, which identified a fighter by its radiation, the thermal direction finder used a completely passive operating principle. The thermal direction finder developed by NPO Geofizika was an optical-electronic device that provided a spatial overview and indicated the location of air targets with subsequent automatic tracking of one of them selected by the pilot. Its operating principle was similar to television sighting systems with a line-frame spatial overview in the IR spectrum. The search for objects was carried out by a sensitive photodetector made in the form of an elemental mosaic of an alloy of indium.antimonide. To increase the sensitivity of the photodetector, deep cooling with liquid nitrogen was used. The TP-23 window was made of optical ceramic plates that formed a characteristic faceted shape of the fairing under the nose of the aircraft. The selection of the "right" object, corresponding to the parameters of thermal radiation of the aircraft engine, was made by the coordinator using spectral and spatial-frequency signal processing, he also issued target designation by target coordinates.

Information on the presence and position of heat-emitting targets was displayed on the glass of the optical sight. A typical target of the Tu-16 type was detected from the rear hemisphere at a distance of at least 30-35 km. However, the TP-23 could be effectively used only under clear weather conditions - dense clouds, fog and precipitation absorbed thermal radiation, making its source barely noticeable to the device.

In addition to searching for targets, the thermal direction finder made it possible to point the radar antenna and issue target designation to the R-23T thermal missiles. It was possible to attack in a completely covert mode without turning on the radar, with aiming based on the TP-23 data. When the thermal direction finder and the radar worked together, the best conditions were created for overcoming the jamming environment - one of the systems was not susceptible to interference, be it radio countermeasures or heat traps, allowing you to select the most suitable operating mode of the search and aiming system for the attack.

TP-23 was installed on vehicles No. 0608 to No. 3508, starting with product No. 3509 it was replaced by the improved TP-23-1, which was distinguished by the design of the coordinator and cooling unit in the form of a monoblock. The thermal direction finder of the modernized design was tested on aircraft No. 3206.
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1737463161293.png

The upgraded TP-23M thermal direction finder (product 26Sh1) had a one and a half times increased range of detection and automatic tracking of air targets, reaching 45 km when operating against targets such as a Tu-16 bomber against a clear sky. The TP-23M had higher accuracy characteristics of no worse than 20 angular minutes and an angular target autotracking speed of up to 6-8 deg/sec, which increased the effectiveness of passive location when working against maneuverable targets. Another advantage was improved protection against natural interference (sunlight, clouds, earth's surface), which made it possible, for example, to detect a target such as the same Tu-16 in the lower hemisphere at a distance of up to 20 km. The role of the thermal direction finder in the S-23ML system expanded: the TP-23M could be used both for space survey and target designation for thermal missiles, and for preparing for an attack using a radar sight, performing a covert approach to the target with the radar antenna pointed at the object with the subsequent activation of the Sapphire and instantaneous target acquisition. The capabilities of the TP-23M even exceeded expectations. The chief designer of the OKB G. A. Sedov reported at a meeting with the military: "In some cases, and not isolated ones, the new thermal direction finders detected and captured targets flying at a distance of 90 km. In conditions of deteriorated visibility, the range of the thermal direction finder on the MiG-23ML aircraft is three times greater than on the MiG-23M aircraft."
Afterburning targets could be detected not only from the rear hemisphere, but also when approaching from the front - when meeting a MiG-25 approaching on afterburner, the detection ranges reached 75 and even 120 km. Externally, the new thermal direction finder was distinguished by a modified fairing with a triangular nose made of optical ceramic plates. Since the usual name of the thermal direction finder TP-23M was given together with its designation as product 26Sh1, at someone's suggestion its incorrect name came into circulation - a contamination of two indexes in the form TP-26Sh1. Despite the absence of such a sample in nature, the fictitious code began to circulate on par with the real one, including in operational documentation - pilot instructions and technical descriptions.
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Viktor Markovsky & Igor Prikhodchenko MiG-23 Fighter - To protect the skies of the Motherland, Eksmo, 2017
 
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overscan (PaulMM) said:
Sitall was a transparent material made in the USSR for optics:
https://en.wikipedia.org/wiki/Sitall
if kemniya is a typo for kremniya then that's silicon.

Google gives three possible translations:

The T-40A1 fairing is made of heat-resistant sitall based on kemnium and optoceramics
The T-40A1 fairing is made of heat-resistant glass-ceramic glass and optoceramics.
The fairing of the T-40A1 is made of heat-resistant glass ceramic based on silicon and optoceramics.
Click to expand...

I cannot thank you enough for this & everything else in this thread :). I did try Google translate & came back with the same results, but Sitall was the part about which I was absolutely clueless, as usual. Really interesting stuff, & it looks like an official study was commissioned in 1994 in order to test its ballistic properties for potential use as some kind of armor -

https://apps.dtic.mil/sti/tr/pdf/ADA280252.pdf
My only question, then, is why was this early faceted/triangular design & material not used, again, & especially now in their more modern irst systems? The necessary pieces are all there, but as always (or at least it feels that way), they're in the wrong place.

Oops, almost forgot - you can literally buy this stuff on eBay from someone in Ukraine, right now.

Unbelievable.
 
If we’re posting TP-23/26sh stuff…..

Its design is really genius. The “missile seeker upscaled in a ball” design of MiG-29/Su-27 is good for dogfighting. But this design using a sensor with 4 lenses mounted on a spinning drum around it to provide very fast azimuth scan, and a servo operated mirror to control vertical scanning gives very fast scanning using the raster scan method and long ranges.

Some photos and pages of MiG-25 manual describing range, radar ranging, and IFF use and other technical docs. MiG-29 is also a downgrade in this respect as the laser takes 8 seconds to try ranging 3 times before it switches to radar ranging, and does not provide you with IFF interrogation or atleast isn’t guaranteed.

The same drum/raster scan design is used In MiG-31 8TK IRST
 

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Yes TP-23 - 8TK in my mind are designed for long range BVR bomber detection and engagement while KOLS/OLS is more about close combat with fighters. Cheers for the drawings and photos.
 
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Yea, you can especially tell the difference with TP-23 handling only 6-8 degrees/s movement, while KOLS in MiG-29 handles up to 30 degrees/s
 
Aeria Gloria said:
If we’re posting TP-23/26sh stuff…..

Its design is really genius. The “missile seeker upscaled in a ball” design of MiG-29/Su-27 is good for dogfighting. But this design using a sensor with 4 lenses mounted on a spinning drum around it to provide very fast azimuth scan, and a servo operated mirror to control vertical scanning gives very fast scanning using the raster scan method and long ranges.

Some photos and pages of MiG-25 manual describing range, radar ranging, and IFF use and other technical docs. MiG-29 is also a downgrade in this respect as the laser takes 8 seconds to try ranging 3 times before it switches to radar ranging, and does not provide you with IFF interrogation or atleast isn’t guaranteed.

The same drum/raster scan design is used In MiG-31 8TK IRST
Click to expand...

Another treasure trove of information. Thank you so much :).
 
Aeria Gloria said:
MiG-29 is also a downgrade in this respect as the laser takes 8 seconds to try ranging 3 times before it switches to radar ranging, and does not provide you with IFF interrogation or atleast isn’t guaranteed.
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Laser rangefinder is a LOT more accurate in ranging than the radar, so it makes sense to try first. Radar ranging is a fallback on the MiG-29.

TP-23 has to rely on the radar for ranging, it has no other choice.
 
Yes, the laser has a lot of accuracy, at the price of its 6.5 km range limit, which makes it very strong in the dogfight and HOBS situation it was designed for. Optimum front aspect range of locking for the IRST however is 12 km, I believe as low in 6-8 km in bad weather and look down.

Su-27 has a shorter range laser of 3 km, but I believe from reading it’s manual that it’s radar will instantaneously range any IRST lock if the Laser Designator is switched off.

MiG-29 has no switch to use IRST without the laser, so needs to try first.

And of course, whether this radar ranging with a ping every 4 seconds or so might set off enemy RWR is a matter of some debate.

I find it an interesting look into doctrine and technology that the TP-23 documents only ever mention rear aspect range with the seeming exception of supersonic afterburner MiG-25, the MiG-29 KOLS documentation only mentions front aspect range, and Su-27 is the only one to mention both front and rear aspect range.
 
The French R.530 and British Red Top AAMs both used cooled Indium Antimonide seekers in the 1960s but both had relatively poor front aspect range except against afterburning targets, just like TP-23M. I haven't yet understood why they are worse than AIM-9L or R-73 in this respect, I assume they're just less sensitive?
 
I realize only one set of range figures was posted

This sheds light to low altitude performance of IRST.

If it can detect a MiG-21 at 180 at 22 km at 10 km alt, and only 9 km at 1 km alt, that is a large difference
 

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overscan (PaulMM) said:
Yes TP-23 - 8TK in my mind are designed for long range BVR bomber detection and engagement while KOLS/OLS is more about close combat with fighters. Cheers for the drawings and photos.
Click to expand...

E.g. 8TK in the MiG-31 could detect SR-71 from 120km away.

https://theaviationgeekclub.com/fox...ept-and-shoot-down-an-sr-71-mach-3-spy-plane/
KOLS in the MiG-29 was only for the front aspect with max 25km detection range. OLS-27 in the Su-27 was for the both forward and rear hemisphere with 100/50 km max detection ranges( AB mode/non- AB mode). We must keep in mind that old Su-27 with R-27T/ET can engage targets in the BVR combat. On the other side, MiG-29 ( 9.12/9.13) couldn't do that.

If this data for TP-23M is right ....

''Afterburning targets could be detected not only from the rear hemisphere, but also when approaching from the front - when meeting a MiG-25 approaching on afterburner, the detection ranges reached 75 and even 120 km.''

...that it was better even than OLS-27. All fighters flying on AB mode could be detected even from forward hemisphere ( TP-23M,TP-26Sh/-1 ).

MiG-23's and MiG-25PD's were better in the BVR with their IRST and IR guided AAM's than MiG-29. Logically, MiG-29 was first real and truly frontal dogfighter.
 
Squirrel said:
KOLS in the MiG-29 was only for the front aspect with max 25km detection range
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Where does this idea come from. All range figures given for it in manual are rear aspect. It is PbSe sensor and likely has front aspect detection only suitable for close WVR combat.

Why do you think MiG-29 can’t use R-27T/ET BVR? The radar aims this missile fine. You will get LP when missile seeker locks and in range. Use Lazur and you just need to fly it and press trigger when it tells you to. You can fire R-73 with radar. No different with T/ET. You don’t need IRST to fire them.Only missile that doesn’t work with radar is 27P/EP.

Since almost none of these give front aspect figures for fighters that aren’t MiG-25 I assume that they were taught to use IRST only or almost entirely on side and rear aspect targets, especially since these radars often have poor rear aspect detection (12-35 km for MiG-29).
 
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^

''KOLS in the MiG-29 was only for the front aspect with max 25km detection range.''

Rear or the 'tail-on' aspect of course, error.
 
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Aeria Gloria said:
Only missile that doesn’t work with radar is 27P/EP.
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Forgot this. P/EP has two working modes .One in conjuction with fighter's radar and another in complete radio-silence mode .

Explained in the article called ''Silent Hunter ''

https://www.secretprojects.co.uk/th...x-r-27-aa-10-alamo-aams.60/page-9#post-884153
Aeria Gloria said:
According to BZPP-4 software 9.12A and 9.12B was capable if it if was loaded but of course T/Et wasn’t sold to 9.12A/9.12B customers.
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It is mistake, even 9.13 wasn't /isn't capable of carrying T/ET. BTsVM's Ts100.02.02/06 lacks one very important detail. Both of them could not recognise ER1 or T1/ET1 at all.


I know for your earlier comment ...

https://www.secretprojects.co.uk/threads/mig-29-avionics.102/page-5#post-790410
But this is another topic and there is some interesting details about TP-23M,from one Russian forum :

''Вместо теплопеленгатора ТП-23 на МЛ был установлен ТП-23М,он же изд.26Ш1,что вызвало некоторую путаницу в названиях. Дальности обнаружения и сопровождения целей были почти одинаковы,но ТП-23М имел несколько большую зону обзора и меньший пеленг на солнце.Надо сказать,что отношение к ТП было двойственным.С одной стороны,многие летчики его хвалили,отмечая,что КОЛС на Миг-29 значительно уступал по дальностям обнаружения/сопровождения.Особенно это сказывалось при высотных перехватах.(КОЛС был больше"заточен" на БВБ,у ТП максимальная угловая скорость цели ограничивалась 6град/сек,для БВБ недостаточно).ТП по дальностям превосходил КОЛС вдвое.Один из летчиков вспоминал,что они уверенно захватывали в ЗПС самолеты,заходящие на посадку,на дальностях около 30км,при этом обороты двигателя у цели были не более 85%,а температура воздуха была под 35градусов.На больших высотах дальность обнаружения в ЗПС могла быть и более 60км.В ППС ТП тоже можно было использовать,но только на средних и больших высотах(высота цели -не менее 8км) с превышением относительно цели,т.к.,ТП был размещен под обтекателем РЛС.Например,при высоте истребителя 15км,цели -11-12км захват происходил на дальностях 15-25км(дальность увеличивалась с увеличением ракурса цели),пуск тепловых ракет -5-15км в зависимости от типа ракет.''

''Instead of the TP-23 thermal direction finder, the ML was equipped with the TP-23M, also known as the 26Sh1 model, which caused some confusion in the naming conventions. The detection and tracking ranges of targets were almost identical, but the TP-23M had a slightly larger field of view and a lower Sun bearing.
It must be said that attitudes toward the TP were ambivalent. On the one hand, many pilots praised it, noting that the MiG-29's KOLS was significantly inferior in detection/tracking ranges. This was especially noticeable during high-altitude interceptions. (The KOLS was more focused on close in combat, while the TP's maximum target angular velocity was limited to 6 degrees/sec, which was insufficient for air defense). The TP's range was twice that of the KOLS.
One of the pilots recalled that they confidently locked onto aircraft approaching for landing at ranges of about 30 km, even though the target's engine rotation was no more than 85% and the air temperature was under 35 degrees. At higher altitudes, the detection range in the ZPS could be over 60 km.
In the PPS, the TP could also be used, but only at medium and high altitudes (target altitude of at least 8 km) with an elevation relative to the target, since the TP was located under the radar fairing. For example, with a fighter altitude of 15 km, the target was 11-12 km, acquisition occurred at ranges of 15-25 km (the range increased with increasing target angle), the launch of heat-seeking missiles - 5-15 km, depending on the type of missile.''

https://rusarmy.com/forum/threads/monografija-o-mig-23.13115/page-2
 
Squirrel said:
Forgot this. P/EP has two working modes .One in conjuction with fighter's radar and another in complete radio-silence mode .

Explained in the article called ''Silent Hunter ''
Click to expand...
He says that. But in MiG-29 it only is allowed to be used by Fi0 mode. If it can be used with host radar, it is not on MiG-29 9.12/9.13 and must be for something else that is more integrated. It is not unusual for Russians to talk about dreams at trade shows.

Squirrel said:
It is mistake, even 9.13 wasn't /isn't capable of carrying T/ET. BTsVM's Ts100.02.02/06 lacks one very important detail. Both of them could not recognise ER1 or T1/ET1 at a
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Yes it and Russian manuals talk about its use on 9.12/13.

Notice 6 pylons; no R-77, this is from 9.13 manual

IMG_0428.png
So it could carry T/ET/P/EP, it is just matter of updating radar block. See description for BZPP-4D, it mentions P/EP and ET.
IMG_0431.jpeg
Squirrel said:
range in the ZPS could be over 60 km.
In the PPS, the TP could also be used, but only at medium and high altitudes (target altitude of at least 8 km) with an elevation relative to the target, since the TP was located under the radar fairing. For example, with a fighter altitude of 15 km, the target was 11-12 km, acquisition occurred at ranges of 15-25 km (the range increased with increasing target angle), the launch of heat-seeking missiles - 5-15 km, depending on the type of missile.''
Click to expand...
Good find. 15-25 km head on is extremely impressive. At low altitude it’s probably less then half that referencing the chart above.

Granted I’m sure those ranges are for afterburner, but Mil power would only be about half that which is still very impressive since it’s likely KOLS detects head on no more then 5-8 km and perhaps twice that in afterburner. I bet it could hit 10 km Mil by 15 degrees off nose in good conditions.
 
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overscan (PaulMM) said:
I consulted my collection of Soviet MiG-23 fighter jet scanning manuals and used an automatic translation function to translate the TP-23 section of the MiG-23M maintenance manual. I only understood the following points:

  • The IRST is a monolithic structure that can be disassembled and maintained as a whole.
  • Both the TP-23 and TP-23-1 were used in the Soviet MiG-23M fighter jet (the TP-23-1 was likely just an improved version).
  • It is cooled by nitrogen gas.
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Hello, could you please provide a user manual? I've been researching this topic recently.

Hello, can you provide the user manual? I've been studying this aspect recently.
 
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